IP forwarding in SuSe 8.0

[Andrew Mathews]

Roger Hayter wrote:

> I wonder if anyone has any ideas what might be going wrong here?  I have 
> a Suse 8.0 machine which I plan to use as a router/firewall.  Using 
> routeable IPs. It has 3 NICs, one of which gets its address by dhcpcd 
> (eth0).  This is for technical adsl modem reasons, but it is always the 
> same address.  IP forwarding works between the two NICs (on different 
> subnets) which have preset IPs (eth1 and eth2), and to the actual IP 
> address of eth0.  Routing is set up so I can contact the wider Internet 
> from the firewall machine itself, via eth0, and both incoming and 
> outgoing connections work fine.  (Not left on long in this un-firewalled 
> config, in case anyone out there is listening!) But the kernel will not 
> accept any packets coming in from eth0 which should go to eth[1 or 2] or 
> vice versa.  It isn't the cards themselves, as I have swapped their 
> roles.  Is this a limitation of dhcp, or can anyone suggest another 
> theory?  I am tempted to try a) Suse 7.3 or b) dhclient instead of 
> dhcpcd, but either would be very laborious.

Two things to check. Make sure that ip forwarding is enabled by doing an
echo "1" > /proc/sys/net/ipv4/ip_forward to enable forwarding and set up 
an ipchains rule such as:
/sbin/ipchains -A forward -s 10.10.108.0/24 -j MASQ
substituting the appropriate address and subnet.

-- 
Andrew Mathews
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